DESCRIPTION: Age-related macular degeneration (AMD) is the leading cause of untreatable blindness in the Western world, with millions affected in the U.S. alone. As the population ages, the negative impact of AMD on society will increase. Unfortunately, the pathogenesis of AMD is currently poorly understood. Because of the prevalence of AMD, and its severe toll on vision, evaluating disease mechanisms in AMD is part of the mission of the National Eye Institute and is highlighted in the 2004 National Plan for Eye and Vision Research. In this project we will examine the role of choriocapillaris activation molecules in AMD. In view of the role of inflammation and the complement system in AMD, we propose to explore the hypothesis that activation of choriocapillaris endothelial cells may be a central event in the pathogenesis of this disease. The first specific aim of this project is to examine the extent and nature of endothelial cell activation in normal eyes and eyes with AMD. Ongoing molecular and histological studies will be performed on normal eyes, early AMD eyes, and advanced AMD eyes. In the second specific aim we will determine whether endothelial cells become activated in culture following exposure to microenvironmental insults that are likely to occur in AMD. Endothelial cell cultures will be challenged with complement complexes (using methodology we have developed) and complement byproducts (anaphylatoxins). The activation response of these cells will be studied using microarrays, immunocytochemistry, real time PCR and Western blotting. In the third specific aim we will test the hypothesis that mutations or polymorphisms in the genes encoding endothelial activation molecules are associated with AMD using a bioinformatics-driven approach. Single nucleotide polymorphisms will be screened in 30 candidate genes (6 per year of the grant). Genetic findings will be followed up using immunohistochemistry and Western blotting of human eyes to examine the possible functional consequences of specific genotypes. Summary: The endothelial cells that comprise blood vessels are likely to play an important role in AMD. One way that these cells promote inflammation is by attracting white blood cells into the inflamed tissue. Endothelial cells perform this role through expression of cell surface proteins that increase in abundance during endothelial "activation". We hypothesize that endothelial cell activation in the eye is responsible for the tissue injury and abnormal blood vessel growth in this disease. Interdisciplinary experiments involving genetics, computer engineering, biochemistry, cell culture and microscopy are expected to provide new information about the potential role of choriocapillaris activation in the development of AMD.